This study presents electrically tunable PN diodes in monolayer WSe₂, demonstrating their potential for optoelectronic applications. The devices are fabricated using two local gates to define a PN junction within a single layer of WSe₂. The PN and NP configurations show current rectification with ideality factors of 1.9, and photodetectors exhibit a responsivity of 210 mA/W and a peak external quantum efficiency of 0.2%. The devices also function as photovoltaic and light-emitting diodes, with the latter emitting light at 752 nm. The monolayer WSe₂ has a direct band gap of ~1.65 eV, making it suitable for optoelectronic applications. The devices are flexible, nearly transparent, and have high performance, making them promising for next-generation optoelectronic devices. The study highlights the potential of monolayer dichalcogenides for flexible, transparent, and efficient optoelectronic applications. The results demonstrate the versatility of monolayer WSe₂ in creating optoelectronic devices with tunable properties. The devices show high performance, including high responsivity and efficiency, and are suitable for low-power electronics. The study also shows the potential for further improvements in device performance through optimized geometry and enhanced contact. The results suggest that monolayer WSe₂ could be a key material for future optoelectronic applications.This study presents electrically tunable PN diodes in monolayer WSe₂, demonstrating their potential for optoelectronic applications. The devices are fabricated using two local gates to define a PN junction within a single layer of WSe₂. The PN and NP configurations show current rectification with ideality factors of 1.9, and photodetectors exhibit a responsivity of 210 mA/W and a peak external quantum efficiency of 0.2%. The devices also function as photovoltaic and light-emitting diodes, with the latter emitting light at 752 nm. The monolayer WSe₂ has a direct band gap of ~1.65 eV, making it suitable for optoelectronic applications. The devices are flexible, nearly transparent, and have high performance, making them promising for next-generation optoelectronic devices. The study highlights the potential of monolayer dichalcogenides for flexible, transparent, and efficient optoelectronic applications. The results demonstrate the versatility of monolayer WSe₂ in creating optoelectronic devices with tunable properties. The devices show high performance, including high responsivity and efficiency, and are suitable for low-power electronics. The study also shows the potential for further improvements in device performance through optimized geometry and enhanced contact. The results suggest that monolayer WSe₂ could be a key material for future optoelectronic applications.